planarian characteristics

Flatworm Characteristics

–Flat bodies (gases move by diffusion)
–bilateral symmetry
–gastrovascular cavity
–some flatworms are parasitic, some are freeliving
–they have anterior and posterior heads and exhibit cephalization


Types of Flatworms (planarian, tapeworm, fluke)

Planarian (also known as Dugesia)–lives in freshwater
–mostly a scavenger, also feeds on protists
–has a simple brain (ganglia) and nervous system, plus 2 eyespots
(see handout on planarian)
–they can regenerate (regrow parts)

Anatomy of the Planarian

Brain (ganglia) – planarian can process information about their environement
Pharynx – used for suckling food in (the mouth is at the end of the pharynx)
Eyespot – simple eye, can detect light
Flame cells – located along the lateral edges, used for excretion
Intestine – digestion (does not have an anus)